Secondary battery

ABSTRACT

A secondary battery includes a battery case, an electrode body, and a collector member connecting the battery case and the electrode body. A positive electrode includes an insulation layer provided so as to be adjacent to a positive electrode active material layer. The collector members include first portions, and second portions continuous to the first portions and bent relative to the first portions. The first portions are fixed to the battery case. The second portions are connected, at ends thereof opposite to the bent portions, to collector regions, respectively. The collector members further include ribs connected, at the bent portions, to the first portions and the second portions, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the priority based on Japanese PatentApplication No. 2019-186940 filed on Oct. 10, 2019, the entire contentsof which are incorporated herein by reference.

BACKGROUND 1. Field of the Invention

The present invention relates to a secondary battery.

2. Description of the Related Art

Secondary batteries such as a lithium ion secondary battery and a nickelmetal hydride battery have been preferably used as the power supply fordriving a vehicle, other than as so-called portable power supplies for apersonal computer, a portable terminal, and the like. As one example ofthe secondary battery, a battery is known in which an electrode bodyincluding a positive electrode and a negative electrode insulated fromeach other by a separator therein is accommodated in a battery case. Theelectrode forming the electrode body has an active material layerincluding an active material at the surface of a collector foil. Herein,in order to enhance the receivability of the electric charge carrier ofa negative electrode active material layer of the low potential side,the negative electrode active material layer is designed so as to have alarger area than that of the positive electrode active material layer.

In this case, the negative electrode active material layer protrudingfrom the positive electrode active material layer has a high deformationfreedom degree. Accordingly, the corner part of the end of the negativeelectrode active material layer may break the separator, and may beshort-circuited with the uncoated part not including a positiveelectrode active material of the positive electrode collector foil. Forexample, WO 2014/162437 discloses a configuration in which an insulationlayer is included in the portion opposed to the negative electrodeactive material layer in the region of the positive electrode collectorfoil adjacent to the positive electrode active material layer in orderto suppress such a short circuit.

SUMMARY

However, observation of the secondary battery actually used has shownthat cracking or peeling may be caused in the insulation layer providedadjacent to the positive electrode active material layer. Further, ithas become obvious that the insulation layer becomes more likely to bepeeled with an increase in cracks of the insulation layer. Peeling ofthe insulation layer is desired to be improved in terms of the reductionof the insulation property between the negative electrode activematerial layer and the positive electrode collector foil.

The present invention has been made in view of such circumstances, andan object of the present invention is to provide a secondary battery inwhich occurrence of cracking and peeling of the insulation layerprovided along the positive electrode active material layer issuppressed.

A study by the present inventors indicated that cracking and peeling ofthe insulation layer provided at the positive electrode collector islargely affected by the vibration of the battery. Namely, in one typicalexample of the secondary battery, the electrode body is positioned inthe battery case by bonding (e.g., welding) the positive electrode sidecollector part and the negative electrode side collector part to thepositive and negative collector members made of a metal attached to thelid member, respectively. However, the electrode body is fixed only atthe welded part with the collector member, and may move or may bedeformed at other parts. Then, the electrode body is the thickest at theoverlapping portion of the positive electrode active material layer andthe negative electrode active material layer. The collector portionwithout the positive electrode active material layer is less restrainedby that much, resulting in a higher deformation freedom degree ascompared with the portion. For this reason, conceivably, when a batteryvibrates, a deviation is caused in vibration between the electrode bodyand the tip of the collector member; accordingly, a load is concentratedto the insulation layer provided at the collector part with a highdeformation freedom degree of the electrode body; this causes crackingand peeling of the insulation layer.

Thus, as the one for solving the problem, a secondary battery hereindisclosed includes: a battery case; an electrode body in which apositive electrode, a negative electrode, and a separator are stacked,with the positive electrode and the negative electrode being insulatedfrom each other by the separator; and a collector member connected tothe battery case and the electrode body. The positive electrodeincludes: a positive electrode collector including an active materiallayer forming region, an insulation layer forming region adjacent to theactive material layer forming region, and a collector region adjacent tothe insulation layer forming region, a positive electrode activematerial layer including a positive electrode active material providedon a surface of the active material layer forming region, and aninsulation layer provided on a surface of the insulation layer formingregion. Further, the collector member includes: a first portion, and asecond portion continuous to the first portion and bent relative to thefirst portion. The first portion is fixed to the battery case, and thesecond portion is connected, at an end thereof on an opposite side tothe bent portion, to the collector region. Then, the collector memberfurther includes a rib connected, at the bent part, to the first portionand the second portion.

With the configuration, the rib is placed across the first portion andthe second portion of the collector member. This suppresses the firstportion and the second portion from being deformed in a direction inwhich the mutually formed angle decreases and a direction in which theangle increases. As a result, when a secondary battery receives avibration, the deviation in vibration of the second portion fixed to theelectrode body with respect to the vibration of the first portion fixedto the case is suppressed. This can reduce the occurrence of cracking orpeeling at the insulation layer onto which the difference in vibrationis concentrated. From the viewpoint that such a collector member caneffectively reduce the occurrence of cracking or peeling of theinsulation layer, the collector member is preferably applied to thepositive electrode collector member to be bonded to the positiveelectrode collector provided with the insulation layer. Further, fromthe viewpoint that such a collector member can more stably support theelectrode body and can further reduce the occurrence of cracking orpeeling of the insulation layer, the collector member is preferablyapplied to both of the positive electrode collector member and thenegative electrode collector member.

Incidentally, the difference in vibration between the first portion andthe second portion of the collector member can also be reduced byenhancing the rigidity of the collector member, e.g., manufacture of thecollector member using a hard material, or increasing the thickness ofthe member. However, a material having a higher rigidity (e.g., Young'smodulus) than that of the constituent material (typically, Al or Alalloy, or Cu or Cu alloy) of a general collector member is not desirablein terms of its high electric resistance. Further, it can be said thatthe increase in thickness of the collector member is undesirable fromthe viewpoint of the cost.

Incidentally, Japanese Patent Application Publication No. 2009-026705discloses as follows: in order to suppress the collector terminal frombeing deformed by a pressing force during welding between the electrodebody and the collector member, and damaging the collector, the flat partincluding the bonding surface of the collector member to be bonded tothe collector is bent. With such a configuration, although the rigidityof the bonding surface of the collector member is enhanced, peeling ofthe insulation layer cannot be suppressed. In terms of this point, thepresent invention is clearly distinguishable in configuration andtechnical idea from the disclosure of Japanese Patent ApplicationPublication No. 2009-026705.

In accordance with one preferable aspect of the technology hereindisclosed, the rib is connected, among surfaces of the first portion andthe second portion, to a surface on an opposite side to the electrodebody. This can effectively suppress the difference in vibration of thecollector with respect to the battery case.

In accordance with one preferable aspect of the technology hereindisclosed, the collector member includes the first portion, the secondportion, and the rib, which are continuously and integrally formed, andis at least one of a bent product and a pressed product of asheet-shaped metal. As a result, a high-strength rib can be constructed.Further, this aspect is also preferable in that the collector member caninclude the rib at a low cost and with efficiency.

In accordance with one preferable aspect of the technology hereindisclosed, the battery case is a square battery case including a casemain body having an opening, and a lid member for covering the opening.The first portion is connected to an inner surface of the lid member,and the second portion is bent along any one surface of the case mainbody surrounding the opening. Then, a length L_(C) from the firstportion to an extreme end of the end and a length L_(R) of a dimensionof the rib in a direction along the length L_(C) satisfy followingrelationship: L_(R)≥0.1×L_(C). With the configuration, it is possible toform a rib capable of effectively suppressing the vibration of the tippart of the collector member.

In accordance with one preferable aspect of the technology hereindisclosed, the battery case is a square battery case including a casemain body having an opening, and a lid member for covering the opening.The first portion is connected to an inner surface of the lid member,and the second portion is bent along any one surface of the case mainbody surrounding the opening. Then, a thickness T_(C) (mm) of adimension in a direction orthogonal to the one surface of the secondportion and a thickness T_(R) (mm) of a dimension in a direction inparallel with the one surface of the rib satisfy following relationship:T_(R)≥0.4×1/T_(C). Also with such a configuration, it is possible toeffectively suppress the bending of the collector member when thesecondary battery receives a vibration.

In accordance with one preferable aspect of the technology hereindisclosed, the battery case is a square battery case including a casemain body having an opening, and a lid member for covering the opening.The first portion is connected to an inner surface of the lid member,and the second portion is bent along any one surface of the case mainbody surrounding the opening. Then, a thickness T_(C) (mm) of adimension in a direction orthogonal to the one surface of the secondportion and a width W_(R) (mm) of a dimension in a direction along thethickness T_(C) of the rib satisfy following relationship:W_(R)≥0.25×1/T_(C). As a result, it is possible to effectively suppressthe bending of the collector member when the secondary battery receivesa vibration.

In accordance with one preferable aspect of the technology hereindisclosed, the electrode body is a wound type electrode body in whichthe positive electrode, the negative electrode, and the separator whichare lengthy are stacked and wound. The wound type electrode bodyincludes a curved part by winding, and hence incurs a higher load at thebonding part with the collector member than that of a sheet typeelectrode body including a plurality of sheet-shaped positive electrode,separator, and negative electrode stacked therein. Therefore, theconfiguration herein disclosed is useful because the configurationclearly produces its effect by being applied to a secondary batteryincluding a wound type electrode body.

The secondary battery described up to this point may remarkably produceits advantageous effects, for example, when used under such environmentas to be applied with a vibration. Further, the short circuit betweenthe negative electrode active material layer and the positive electrodecollector tends to become problematic for a battery in which thethickness of the electrode body is large, and the end of the negativeelectrode active material layer tends to be applied with a bendingforce, in other words, a high capacity battery. Further, a reliablemeasure for suppressing the short circuit has been demanded. Stillfurther, measures have been demanded particularly for suppressing thebattery temperature rise due to the microscopic short circuit in asecondary battery for uses requiring high safety. From such a viewpoint,the secondary battery herein disclosed can be in particular preferablyused as power supply (main power supply) for driving a vehicle,especially, power supply for driving a hybrid vehicle, a plug-in hybridvehicle, an electric vehicle, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutaway perspective view schematically showing aconfiguration of a secondary battery in accordance with one embodiment;

FIG. 2 an essential part side view of the secondary battery inaccordance with one embodiment;

FIG. 3A is a side view of a collector member in accordance with oneembodiment, and FIG. 3B is a cross sectional view along B-B in FIG. 3A;

FIG. 4 is a partially developed view for illustrating a configuration ofa wound type electrode body in accordance with one embodiment;

FIG. 5 is a cross sectional schematic view for illustrating aconfiguration of an electrode body in accordance with one embodiment;and

FIGS. 6A, 6B, and 6C are schematic views for illustrating aconfiguration of each collector member in accordance with otherembodiments, respectively.

DETAILED DESCRIPTION

Below, one embodiment of a secondary battery herein disclosed will bedescribed. Incidentally, matters necessary for executing the presentinvention (e.g., a structure of the secondary battery not featuring thepresent invention), except for matters specifically referred to in thepresent specification (e.g., configurations, and the like of aninsulation layer and a collector member) can be grasped as designmatters of those skilled in the art based on the related art in thepresent field. The present invention can be executed based on thecontents disclosed in the present specification and the technical commonsense in the present field. Further, the dimensional relation (such aslength, width, or thickness) in each drawing shown below does notreflect the actual dimensional relation. Then, an expression “A to B”indicating the numerical value range in the present specification means“A or more and B or less”.

In the present specification, “secondary battery” is a term denoting anelectric storage device capable of repeatedly charging and dischargingin general, and including a so-called storage battery such as a lithiumion battery, a sodium ion secondary battery, or a lithium polymerbattery, and electric storage elements such as an electric double layercapacitor. Further, “nonaqueous electrolyte secondary battery” is asecondary battery implementing charging and discharging using anonaqueous electrolyte as an electric charge carrier. The electrolytemay be any of a solid electrolyte, a gel electrolyte, and a nonaqueouselectrolyte. Further, the “active material” represents a substancecapable of reversibly occluding and releasing chemical species servingas an electric charge carrier in a secondary battery. Below, the presenttechnology will be described by taking the case where a nonaqueouselectrolyte secondary battery is a lithium ion secondary battery as anexample.

FIG. 1 is a cutaway perspective view showing a configuration of alithium ion battery (which will be simply referred to as a “secondarybattery”) 1 in accordance with one embodiment. FIG. 2 is an essentialpart side view thereof. FIG. 3A is a side view showing a configurationof a collector terminal, and FIG. 3B is a B-B cross sectional viewthereof. FIG. 4 is a partially developed view for illustrating aconfiguration of a wound type electrode body 20, and FIG. 5 is a crosssectional view thereof. W in the drawing indicates the width directionof a battery case 10 and a wound type electrode body 20, and is inagreement with the direction of a winding axis WL of the wound typeelectrode body 20. H represents the height direction of the battery case10. Further, the winding axis WL and the direction orthogonal to theheight direction of the battery case 10 may be referred to as thethickness directions of the battery case 10 and the wound type electrodebody 20. However, the directions do not restrict the setting aspects ofthe secondary battery at all.

The lithium ion secondary battery 1 is configured such that the woundtype electrode body 20 including the positive electrode 30, the negativeelectrode 40, and the separator 50 is accommodated in the battery case10 together with a nonaqueous electrolyte not shown. The wound typeelectrode body 20 has a shape in which the separator 50, the negativeelectrode 40, the separator 50, and the positive electrode 30 aresequentially stacked in this order, and are wound in an elliptical shapein cross section about the winding axis WL as the center. For theelectrode body 20, respective collector regions 32 c and 42 c ofcollectors 32 and 42 described later protrude to both ends in the widthdirection. The electrode body 20 is connected to the collector members38 and 48 at the collector regions 32 c and 42 c, respectively, and isfixed to the battery case 10.

The positive electrode 30 typically includes the positive electrodecollector 32, and porous, and an insulation layer 36 is included thereinso as to be adjacent to the positive electrode active material layer 34.The positive electrode collector 32 is a support member of the positiveelectrode active material layer 34, and can be a conductive member forextracting electric charges from the positive electrode active materiallayer 34. For the positive electrode collector 32, for example, metalfoil such as aluminum (including aluminum alloy) foil is preferablyused. The positive electrode collector 32 includes an active materiallayer forming region 32 a, an insulation layer forming region 32 b, anda collector region 32 c. The active material layer forming region 32 aoccupies the most part of the positive electrode collector 32, theinsulation layer forming region 32 b is adjacent to the active materiallayer forming region 32 a, and the collector region 32 c is adjacent tothe insulation layer forming region 32 b. The positive electrodecollector 32 of this example is long, and is divided in the widthdirection in the order of the active material layer forming region 32 a,the insulation layer forming region 32 b, and the collector region 32 c.As one example, the dimension in the width direction of the insulationlayer forming region 32 b is about 2.7 to 6 mm, and the dimension in thewidth direction of the collector region 32 c is about 8.5 to 12.5 mm.The positive electrode active material layer 34 is formed in a bandshape on the surface of the active material layer forming region 32 a.The insulation layer 36 is formed in a band shape on the surface of theinsulation layer forming region 32 b. In the collector region 32 c, thecollector is exposed.

The positive electrode active material layer 34 contains a particulatepositive electrode active material. The positive electrode activematerial layer 34 is configured as follows: positive electrode activematerials are bound to one another by a binder, and are bound to theactive material layer forming region 32 a. The pores of the positiveelectrode active material layer 34 are impregnated with a nonaqueouselectrolyte. As the positive electrode active materials, for example,one or combinations of two or more of lithium transition metal compositeoxides such as lithium nickel cobalt manganese composite oxides (e.g.,LiNi_(1/3)Co_(1/3)Mn_(1/3)O₂), lithium nickel composite oxides (e.g.,LiNiO₂), lithium cobalt composite oxides (e.g., LiCoO₂), and lithiumnickel manganese composite oxides (e.g., LiNi_(0.5)Mn_(1.5)O₄) capableof reversibly occluding/releasing lithium ions are used. The positiveelectrode active material layer 34 can contain, other than the positiveelectrode active material, a conductive material such as acetylene black(AB), a binder such as an acrylic polymer, polyvinylidene fluoride(PVDF), or styrene butadiene rubber (SBR) for binding these, and otheradditives.

The thickness of the positive electrode active material layer 34 afterpressing (which is the average thickness; the same shall applyhereinafter.) can be set at typically 10 μm or more, for example, 15 μmor more, and typically 50 μm or less, 30 μm or less, for example, 25 μmor less. Further, the density of the positive electrode active materiallayer 34 has no particular restriction, and can be set at typically 1.5g/cm³ or more, for example, 2 g/cm³ or more and 3 g/cm³ or less, and forexample, 2.5 g/cm³ or less.

Incidentally, in the present specification, “average particle diameter”represents the cumulative 50% particle diameter (D₅₀) in thevolume-based particle size distribution obtained by the laserdiffraction scattering method unless otherwise specified.

The insulation layer 36 has electric insulation property, and isconfigured so as to be able to prevent a short circuit between the endof the negative electrode active material layer 44 and the positiveelectrode collector 32, for example, even when the separator 50 isbroken, or the separator 50 is dissolved/shrunk, or the like. Theinsulation layer 36 is configured such that inorganic fillers aremutually bound by a binder, and bound with the insulation layer formingregion 32 b. The insulation layer 36 may be a porous layer enablingpassage of electric charge carriers therethrough. The insulation layer36 is provided in the region adjacent to the positive electrode activematerial layer 34, and opposed to at least the negative electrode activematerial layer 44. The insulation layer 36 may protrude outwardly of thenegative electrode active material layer 44 in the width direction by adimension α. The dimension α is designed at the dimension capable ofallowing sufficient covering of the end of the negative electrode activematerial layer 44 by the insulation layer 36 so as to avoid thesituation in which the negative electrode active material layer 44 andthe positive electrode collector 32 are opposed to each other via onlythe separator 50 even when misalignment is caused for the negativeelectrode active material layer 44. The dimension a may desirablydesigned at a dimension enough to prevent the insulation layer 36 fromprotruding from the end of the separator 50 in order to avoid poor foilcollection of the collector 32 (collector region 32 c).

Examples of the inorganic fillers forming such an insulation layer 36may include inorganic oxides such as alumina (Al₂O₃), magnesia (MgO),silica (SiO₂), and titania (TiO₂), clay minerals such as mica, talk,boehmite, zeolite, apatite, and kaolin, and glass materials. Out ofthese, boehmite (Al₂O₃·H₂O), alumina (Al₂O₃), and the like which havestable quality, and further are low-priced, and readily available arepreferably used. Incidentally, the parenthesized molecular formula is atypical composition, and the present invention is not necessarilylimited to this composition. Any one of these may be included alone, ortwo or more thereof may be included in combination. As the binders to beincluded in the insulation layer 36, for example, various binders usablefor the positive electrode active material layer can be preferably used.The proportion of the binder included in the insulation layer 36 is, forexample, typically 1 mass % or more, preferably 5 mass % or more, andmay be 8 mass % or more, 10 mass % or more, or the like. The binderincluded in the insulation layer 36 is in an amount of, for example,typically 30 mass % or less, may be 25 mass % or less, or may be 20 mass% or less, 18 mass % or less, or 15 mass % or less. As one typicalexample thereof, the amount may be appropriately adjusted at 5 to 20mass %. The thickness of the insulation layer 36 may be typically 20 μmor less, for example, 18 μm or less, 15 μm or less, or 10 μm or less(e.g., less than 10 μm), or may be set at 8 μm or less, for example, 6μm or less, or 5 μm or less. The thickness of the insulation layer 36may be typically 3 μm or more. Incidentally, such an insulation layer 36may have a weight per unit area of about 0.5 mg/cm² or more, 0.7 mg/cm²or more, 1 mg/cm² or more, or the like, and 1.5 mg/cm² or less, 1.3mg/cm² or less, 1.2 mg/cm² or less, or the like.

The negative electrode 40 can include typically a negative electrodecollector 42, and porous negative electrode active material layers 44formed on both surfaces thereof. Specifically, the negative electrodecollector 42 includes an active material layer forming region 42 a and acollector region 42 c. The active material layer forming region 42 aoccupies the most part of the negative electrode collector 42, and thecollector region 42 c is adjacent to the active material layer formingregion 42 a. The negative electrode collector 42 of this example islong, and is divided in the width direction into the active materiallayer forming region 42 a and the collector region 42 c. As one example,the dimension in the width direction of the collector region 42 c isabout 8 to 12 mm. The negative electrode active material layer 44 isformed in a band shape on the surface of the active material layerforming region 42 a. In the collector region 32 c, the collector isexposed. The pores of the negative electrode active material layer 44are impregnated with a nonaqueous electrolyte. For the negativeelectrode collector 42, for example, metal foil such as copper foil ispreferably used.

The negative electrode active material layer 44 contains a particulatenegative electrode active material. As the negative electrode activematerials, for example, one, or combinations of two or more of carbontype materials such as graphite carbon and amorphous carbon, silicon,lithium transition metal oxide, and lithium transition metal nitride,capable of reversibly occluding/releasing lithium ions are used. Thenegative electrode active material layer 44 may include, other than thenegative electrode active material, a binder such as polyvinylidenefluoride (PVDF), or styrene butadiene rubber (SBR), or a thickener suchas carboxymethyl cellulose (CMC), for binding these. The thickness afterpressing of the negative electrode active material layer 44 (which isthe average thickness of one side; the same shall apply hereinafter.)may be, for example, 20 μm or more, typically 40 μm or more, forexample, from the viewpoint of an increase in capacity, 50 μm or more.The average thickness of the negative electrode active material layer 44may be, for example, 100 μm or less, typically, 80 μm or less, forexample, 65 μm or less. Further, the density of the negative electrodeactive material layer 44 has no particular restriction, and can be setat, for example, 0.8 g/cm³ or more, typically, 1.0 g/cm³ or more, and1.5 g/cm³ or less, typically, 1.4 g/cm³ or less, for example, 1.2 g/cm³or less.

The separator 50 is a constituent element for insulating the positiveelectrode 30 and the negative electrode 40 from each other, andproviding a migration path for electric charge carriers between thepositive electrode active material layer 34 and the negative electrodeactive material layer 44. Such a separator 50 is arranged between thepositive electrode active material layer 34 and the negative electrodeactive material layer 44. Such a separator 50 can be preferably formedof a microporous resin sheet including a resin such as polyethylene(PE), polypropylene (PP), polyester, cellulose, or polyamide. Out ofthese, a microporous sheet including a polyolefine resin such as PE orPP is preferable because the shutdown temperature can be preferably setwithin the range of 80° C. to 140° C. (typically, 110° C. to 140° C.,for example, 120° C. to 135° C.). Such a separator 50 may have amonolayer structure including a single material, or may have a structureof lamination of two or more microporous resin sheets having differentmaterial qualities and properties (e.g., average thickness and porosity)(e.g., a three-layered structure in which PP layers are stacked on bothsurfaces of a PE layer). The thickness (which is the average thickness;the same shall apply hereinafter.) of the separator 50 has no particularrestriction, and can be set at, generally 10 μm or more, typically, 15μm or more, for example, 17 μm or more. Further, the upper limit can beset at 40 μm or less, typically, 30 μm or less, for example, 25 μm orless. The average thickness of the base material falls within theforegoing range. As a result, the permeability of the electric chargecarrier can be kept good, and microscopic short circuit (leakagecurrent) becomes less likely to be caused. For this reason, the inputoutput density and the safety can be combined at a high level.

Incidentally, in the electrode body 20, the width W1 of the positiveelectrode active material layer 34, the width W2 of the negativeelectrode active material layer 44, and the width W3 of the separator 50satisfy the relationship of W1<W2<W3. Further, the negative electrodeactive material layer 44 covers the positive electrode active materiallayer 34 at the opposite ends thereof in the width direction, and theseparator 50 covers the negative electrode active material layer 44 atthe opposite ends thereof in the width direction. Further, theinsulation layer 36 covers the positive electrode collector 32 at leastin the region opposed to the end of the negative electrode activematerial layer 44 while being adjacent to the positive electrode activematerial layer 34. However, the electrode body of the lithium ionsecondary battery 1 herein disclosed is not limited to a wound typeelectrode body, and may be an electrode body of a so-called flat-platelamination type, for example, in a form in which a plurality of positiveelectrodes 30 and negative electrodes 40 are respectively insulated bythe separators 50, and are stacked.

The nonaqueous electrolyte includes a nonaqueous solvent and anelectrolyte support salt. The nonaqueous solvent and the electrolytesupport salt have no particular restriction on the kind, and may be thesame as those used for the electrolyte of a conventional secondarybattery. Preferable examples of the electrolyte support salt includelithium salts such as LiPF₆ and LiBF₄. Preferable examples of thenonaqueous solvent include aprotic solvents such as carbonates, esters,and ethers. Out of these, cyclic carbonates such as ethylene carbonate(EC) and propylene carbonate (PC), chain carbonates such as diethylcarbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate(EMC), and fluorinated chain or fluorinated cyclic carbonates obtainedby fluorinating the carbonates are preferably included each alone, ortwo or more thereof. The concentration of the lithium salt in theelectrolyte can be set at, for example, 0.8 to 1.3 mol/L. The nonaqueouselectrolyte can include additives such as a film forming agent and anovercharge inhibitor other than these.

The battery case 10 includes a case main body 11 having an opening at afirst surface (herein, the top surface), and a lid member 12 for sealingthe opening. The case main body 11 of this example is of a flat bottomedsquare tube type including a bottom surface 11 c, a pair of wide sidesurfaces 11 a continuous to the bottom surface 11 c, and wide in thewidth direction, and one narrow side surface 11 b continuous to thebottom surface 11 c and the wide side surface 11 a. The lid member 12 isformed so as to be able to hermetically seal the opening formed by theupper ends of the wide side surface 11 a and the narrow side surface 11b. The lid member 12 is equipped with a positive electrode externalterminal 38T and a negative electrode external terminal 48T, aninjection hole, and a safety valve. Although the battery case 10 is notlimited to this, the battery case 10 is preferably formed of, forexample, a metal such as iron, copper, aluminum, or titanium, and analloy including these (e.g., steel), or a high strength resin.

The positive electrode external terminal 38T and the negative electrodeexternal terminal 48T are electrically connected with the positiveelectrode collector member 38 and the negative electrode collectormember 48 provided on the case inside side, respectively, while beinginsulated from the lid member 12. The terminal structures on thepositive electrode side and on the negative electrode side are mostlyidentical with each other. For this reason, below, by taking thepositive electrode side as an example, the terminal structure and thecollector members 38 and 48 will be described. The following descriptionon the positive electrode collector member 38 similarly applies to thenegative electrode collector member 48. Although the details areomitted, with the terminal structure of a typical secondary battery 1,as shown in FIG. 2 , from the case outside (herein, the top), thepositive electrode external terminal 38T, an external insulation member(not shown), the lid member 12, an internal insulation member (notshown), and the positive electrode collector member 38 are stacked inthis order, and a hole not shown is provided coaxially. Then, a caulkingmember 38K (see FIG. 6A) made of a metal, inserted into this holeintegrally and tightly caulks these. As a result, each member is fixedto the lid member 12. Herein, the positive electrode collector member 38is electrically connected with the positive electrode external terminal38T by the caulking member 38K. The external insulation member and theinternal insulation member are mechanically connected with each other bythe caulking member 38K. As a result, the positive electrode externalterminal 38T, the positive electrode collector member 38, and thecaulking member 38K are electrically insulated from the lid member 12 bythe external insulation member and the internal insulation member.Incidentally, the caulking member 38K may also be previously integrallyprovided on the top surface of a first portion 38 a of the collectormember 38 as shown in FIGS. 6A, 6B, and 6C. The caulking member 38K issubjected to chalking, so that the protrusion amount from the topsurface of the first portion 38 a is reduced (see, FIG. 1 , or thelike).

The positive electrode collector member 38 includes the first portion 38a and a second portion 38 b. The first portion 38 a and the secondportion 38 b are generally in a sheet shape. The positive electrodecollector member 38 is fixed to the lid member 12 of the battery case 10by the first portion 38 a as described above. The second portion 38 b iscontinuous to the first portion 38 a, and is bent with respect to thefirst portion 38 a. The portion between the first portion 38 a and thesecond portion 38 b is a bent part 38L. The positive electrode collectormember 38 of the present embodiment is bent to about 90° at the bentpart 38L. The second portion 38 b extends downwardly along the wide sidesurface 11 a of the case main body 11. The second portion 38 b is curvedin a substantially S shape inwardly of the battery case 10 at aprescribed-length downward extension thereof. Then, at the end 38 eunder the curved part 38S, the second portion 38 b extends downwardlyalong the wide side surface 11 a again. The second portion 38 b isbonded with the collector region 32 c of the wound type electrode body20 at the flat-sheet-shaped end 38 e under the curved part 38S. Withsuch a configuration, the positive electrode collector member 38 can beconfigured as follows: the curved part R of the wound type electrodebody 20 can be arranged in the space formed between the first portion 38a and the curved part 38S, so that the wound type electrode body 20 canbe supported and fixed without breaking the curved part R. Incidentally,the positive electrode collector member 38 and the collector region 32 cof the electrode body 20 are preferably connected with each other byultrasonic welding. Further, the negative electrode collector member 48and the collector region 42 c of the electrode body 20 are preferablyconnected with each other by resistance welding. As a result, in thesecondary battery 1, an electric energy can be charged to the electrodebody 20, and an electric energy can be extracted from the electrode body20 to an external circuit through the positive electrode externalterminal 38T and the negative electrode external terminal 48T.

The positive electrode collector member 38 further includes a rib 38 cconnected to the first portion 38 a and the second portion 38 b at thebent part 38L. The rib 38 c is a small-piece-shaped portion. The rib 38c is, as shown in FIG. 3A, placed across the first portion 38 a and thesecond portion 38 b. The rib 38 c is disposed so as to be orthogonal toat least one, preferably both of the first portion 38 a and the secondportion 38 b. In the present embodiment, the rib 38 c is connected tothe surfaces of the first portion 38 a and the second portion 38 b eachon the side thereof opposed to the electrode body 20. Such aconfiguration can preferably suppress the second portion 38 b fromrelatively rocking with respect to the first portion 38 a. In otherwords, the first portion 38 a and the second portion 38 b are suppressedfrom being deformed in a direction in which the mutually formed angle(θ) decreases (e.g., θ<90°) and a direction in which the angle increases(e.g., θ>90°).

Although such a rib 38 c is not limited thereto, preferably, the firstportion 38 a, the second portion 38 b, and the rib 38 c are continuouslyand integrally formed. Namely, although the first portion 38 a, thesecond portion 38 b, and the rib 38 c of the positive electrodecollector member 38 may be formed of different members bonded together,these may be formed by processing one sheet-shaped metal member by atleast one of bending and pressing. In other words, the positiveelectrode collector member 38 may be at least one of a bent product anda pressed product. As a result, a joint is not formed at the firstportion 38 a, the second portion 38 b, and the rib 38 c. This ispreferable because when a vibration is applied to the secondary battery1, a fault such as breakage of the joint due to stress concentration tothe joint is accordingly less likely to be caused. Incidentally, anythose skilled in the art can confirm whether the first portion 38 a, thesecond portion 38 b, and the rib 38 c of the positive electrodecollector member 38 are manufactured by bending and/or pressing or notby observing the metal structure.

Below, the results of a study on the shapes of the ribs 38 c and 48 c ofthe collector members 38 and 48 will be shown, and preferable shapes ofthe ribs 38 c and 48 c will be described.

As shown in FIG. 3A, for each length of the second portions 38 b and 48b of the collector members 38 and 48, the distance from (each surface onthe rib side of) the first portions 38 a and 48 a to each extreme end ofthe ends 38 e and 48 e of the second portions 38 b and 48 b is referredto as the length L_(C) (distance L_(C)) of the second portions 38 b and48 b. Namely, the length L_(C) of the second portion 38 b or 48 b is thedimension not in view of the curve length of the curved part 38S.Whereas, for each thickness of the second portions 38 b and 48 b, eachdimension of the second portion 38 b and 48 b in a direction orthogonalto the wide side surface 11 a is referred to as the thickness T_(C)(mm). For each length of the ribs 38 c and 48 c, each dimension of theribs 38 c and 48 c in a direction along the length L_(C) is referred toas the length L_(R) (mm) of the ribs 38 c and 48 c. For each thicknessof the ribs 38 c and 48 c, the dimension in a direction in parallel withthe wide side surface 11 a is referred to as the thickness T_(R) (mm) ofthe ribs 38 c and 48 c. For each width of the ribs 38 c and 48 c, thedimension in a direction along the thickness T_(C) of the secondportions 38 b and 48 b is referred to as the width W_(R) (mm).

Rib Length

For the collector member with the length L_(R) of the rib changed infive ways, and also for the collector member not provided with a rib, avibration test was conducted under the following conditions, therebymeasuring the displacement amount of the extreme end of the secondportion. The results are shown in Table 1 below as relative values withthe displacement amount of the extreme end of the second portion whenthe vibration test was conductive for the collector member without a ribas “100”. Then, the case where the relative value of the displacementamount is 20 or less is assumed as a sufficient vibration suppressingeffect (success: “AA” in Table 1), and the case where the relative valueof the displacement amount is more than 20 is assumed as an insufficientvibration suppressing effect (failure: “CC” in Table 1).

Incidentally, the thickness T_(R) of the rib of the collector member wasassumed to be constant at “0.4/T_(C)” with respect to the thicknessT_(C) of the second portion, and the width W_(R) of the rib was assumedto be constant at “0.47/T_(C)” with respect to the thickness T_(C) ofthe second portion.

Vibration Test Conditions

Acceleration: 10 G

Frequency: 25 Hz

Temperature: room temperature (25° C.)

Vibration direction: width direction of rib (thickness direction ofsecond portion)

TABLE 1 Sample 1 2 3 4 5 6 Rib length None 0.04 L_(C) 0.07 L_(C) 0.10L_(C) 0.13 L_(C) 0.16 L_(C) L_(R) Displacement 100 70 50 20 15 10 amount[−] Evaluation CC CC CC AA AA AA

As shown in Table 1, it has been confirmed as follows: by setting thelength L_(R) of the rib at 0.1 time or more (L_(R)≥0.1×L_(C)) withrespect to the length L_(C) of the second portion, it is possible toeffectively suppress the vibration. Although not specifically shown, thesame tendency can also be observed for the case where the test isconducted for a collector member having different specifications such asshape and dimension. The length L_(R) of the rib is preferablyL_(R)≥0.12×L_(C), more preferably L_(R)≥0.15×L_(C), or L_(R)≥0.2×L_(C),and may be set at, for example, L_(R)≥0.3×L_(C), or L_(R)≥0.5×L_(C). Theupper limit of the length L_(R) of the rib can be determined in view ofthe allowable dimension of the battery case within the range in whichthe curved part R of the electrode body 20 and the rib do not interferewith each other. For example, the upper limit of the length L_(R) of therib may be 1×L_(C), and examples thereof may include about 0.9×L_(C) and0.8×L_(C).

Rib Thickness

For the collector members with the thickness T_(R) of the rib changed insix ways, and also for the collector member not provided with a rib, avibration test was conducted under the same conditions as thosedescribed above, thereby measuring the displacement amount of theextreme end of the second portion. The results are shown in Table 2below as relative values with the displacement amount of the extreme endof the second portion when the vibration test was conductive for thecollector member without a rib as “100”. Then, the case where therelative value of the displacement amount is 20 or less is assumed as asufficient vibration suppressing effect (success: “AA” in Table 2), andthe case where the relative value of the displacement amount is morethan 20 is assumed as an insufficient vibration suppressing effect(failure: “CC” in Table 2).

Incidentally, the length L_(R) of the rib of the collector member wasassumed to be constant at “0.1×L_(C)” with respect to the thicknessT_(C) of the second portion, and the width W_(R) of the rib was assumedto be constant at “0.47/T_(C)” with respect to the thickness T_(C) ofthe second portion.

TABLE 2 Sample 1 2 3 4 5 6 7 Rib thickness  0 0.1/T_(C) 0.2/T_(C)0.4/T_(C) 0.48/T_(C) 0.56/T_(C) 0.8/T_(C) T_(R) Displacement 100 50 4020 20 15 15 amount [−] Evaluation CC CC CC AA AA AA AA

As shown in Table 2, it has been confirmed as follows: by setting thethickness T_(R) of the rib at 0.4 time or more (T_(R)≥0.4×1/T_(C)) withrespect to the inverse (1/T_(C)) of the thickness T_(C) of the secondportion as shown in, for example, Table 2, it is possible to effectivelysuppress the vibration. Although not specifically shown, roughly thesame tendency can also be observed for the case where the test isconducted for a collector member having different specifications such asshape and dimension. This thickness T_(R) of the rib is preferablyT_(R)≥0.45/T_(C), more preferably T_(R)≥0.48/T_(C), and may be, forexample, T_(R)≥0.5/T_(C), T_(R)≥0.55/T_(C), T_(R)≥0.6/T_(C),T_(R)≥0.7/T_(C), or T_(R)≥0.8/T_(C). The upper limit of the thicknessT_(R) of the rib can be determined in view of the processability of thecollector member, the connectivity with the electrode body, and thelike. As one example, when the rib is too thick, it becomes difficult toform the rib by extrusion. Further, when the rib is too thick, theconnection between the electrode body and the collector member maybecome difficult. From such viewpoints, the upper limit of the thicknessT_(R) of the rib may be set, for example, with about ⅓ the width of thecollector member (the dimension in the direction orthogonal to thelength L_(C) and the thickness T_(C)) as a guide. The thickness T_(R) ofthe rib may be 2/7 or less, ¼ or less, ⅕ or less the width of thecollector member, or the like.

Rib Width

For the collector members with the width W_(R) of the rib changed in sixways, and also for the collector member not provided with a rib, avibration test was conducted under the same conditions as thosedescribed above, thereby measuring the displacement amount of theextreme end of the second portion. The results are shown in Table 3below as relative values with the displacement amount of the extreme endof the second portion when a vibration test was conductive for thecollector member without a rib as “100”. Then, the case where therelative value of the displacement amount is 20 or less is assumed as asufficient vibration suppressing effect (success: “AA” in Table 3), andthe case where the relative value of the displacement amount is morethan 20 is assumed as an insufficient vibration suppressing effect(failure: “CC” in Table 3).

Incidentally, the length L_(R) of the rib of the collector member wasassumed to be constant at “0.1×L_(C)” with respect to the length L_(C)of the second portion, and the thickness T_(R) of the rib was assumed tobe constant at “0.4/T_(C)” with respect to the thickness T_(C) of thesecond portion.

TABLE 3 Sample 1 2 3 4 5 6 7 Rib thickness  0 0.17/T_(C) 0.25/T_(C)0.33/T_(C) 0.47/T_(C) 0.58/T_(C) 0.83/T_(C) W_(R) Displacement 100 60 2020 15 15 10 amount [−] Evaluation CC CC AA AA AA AA AA

As shown in Table 3, it has been confirmed as follows: by setting thewidth W_(R) of the rib at 0.25 time or more (W_(R)≥0.25×1/T_(C)) withrespect to the inverse (1/T_(C)) of the thickness T_(C) of the secondportion, it is possible to effectively suppress the vibration. Althoughnot specifically shown, the same tendency can also be observed for thecase where the test is conducted for a collector member having differentspecifications such as shape and dimension. The width W_(R) of the ribis preferably W_(R)≥0.3/T_(C), more preferably W_(R)≥0.4/T_(C), orW_(R)≥0.5/T_(C), and may be, for example, W_(R)≥0.6/T_(C),W_(R)≥0.8/T_(C), or W_(R)≥1/T_(C). The upper limit of the width W_(R) ofthe rib can be determined in view of the processability of the collectormember, the accommodability in the case, and the like. As one example,when the width W_(R) of the rib is too large, it becomes difficult toform the rib by extrusion. Further, a too large width W_(R) of the ribmay cause interference between the case covering the electrode body, aninsulation film (not shown), or the like and the rib upon accommodatingthe electrode body in the case or in the case, and hence is notpreferable. From such a viewpoint, the upper limit of the width W_(R) ofthe rib can be set at a dimension capable of avoiding such interference.The width W_(R) of the rib may desirably be set to be, for example,about ½, or may desirably be set about ⅓ or less the thickness of theelectrode body (the dimension in each direction orthogonal to thewinding axis WL and the height direction H). Further, the width W_(R) ofthe rib may desirably be set to be, for example, about ½, or also may bedesirably set at about ⅓ or less the dimension of the second portion inthe thickness direction (each direction orthogonal to the winding axisWL and the height direction H).

In the embodiment, the rib 38 c was, as shown in FIG. 3A, a rectangularsheet-shaped body as seen from the direction along the wide side surface11 a. However, the shape of the rib 38 c is not limited to this. Forexample, the rib 38 c may lack the end of the portion connected to thefirst portion 38 a and the second portion 38 b in the region opposite tothe bent part 38L across the line connecting two ends opposite to thebent part 38L. For example, the rib 38 c may be a triangle formed byconnecting the bent part 38L and the two ends on the opposite side,respectively. Further, for example, for the rib 38 c, the corner partnot connected to the first portion 38 a and the second portion 38 b maybe subjected to chamfering. The chamfering may be chamfering of onecorner part of the rectangle into an R surface or a C surface, or may bechamfering into an R surface so as to gently connecting the two ends onthe opposite side (i.e., to form the rectangle into a fan shape).Further, in the example shown in FIG. 3B, the rib 38 c is provided so asto be connected to the end of the second portion 38 b on the sidethereof farther from the center in the width direction of the batterycase. However, the position of the rib 38 c is not limited to this. Therib 38 c may be provided at the end of the second portion 38 b closer tothe center in the width direction of the battery case, or may beprovided so as to be connected to the center in the width direction ofthe second portion 38 b, or to other positions.

In the embodiment, only respective ones of ribs 38 c and 48 c areprovided at the collector members 38 and 48, respectively. However,respective two or more of the ribs 38 c and 48 c may be provided atrespective ones of the collector members 38 and 48, respectively. Forexample, in the example shown in FIG. 3B, one rib 38 c is provided atone positive electrode collector member 38. However, the number of theribs 38 c is not limited to this. Two or more, for example, a pluralityof such as two, three, or four ribs 38 c may be provided at one positiveelectrode collector member 38. In this case, all the ribs 38 c may havethe same shape, or one or some ribs 38 c may independently havedifferent shapes. When there are a plurality of ribs 38 c, respectiveribs 38 c may be desirably arranged dispersed in the width direction (W)of the second portion 38 b so as to preferably suppress the fluctuationsin angle formed between the first portion 38 a and the second portion 38b. For example, the ribs 38 c may be arranged at regular intervals inthe width direction of the second portion 38 b. Incidentally, when thefirst portion 38 a and the second portion 38 b are connected to eachother not in an L shape in cross section but in a T shape in crosssection at the bent part 38L thereof, the ribs 38 c may be provided atonly one surface of the second portion 38 b, or may be provided at bothsurfaces thereof (see FIG. 6B). In this case, for each thickness T_(R)and each width W_(R) of the ribs 38 c and 48 c, each total thicknessT_(R) and each total width W_(R) of respective two or more ribs 38 c and48 c preferably fall within the respective ranges.

In the embodiment, the second portions 38 b and 48 b of the collectormembers 38 and 48 were each in the shape of a rectangle (in the shape ofa band) longer in the height direction as seen from the side of the wideside surface. However, each shape of the second portions 38 b and 48 bas seen from the side of the wide side surface may also be in othershapes than a rectangle. For example, at each portion closer to the bentparts 38L and 48L, each width of the second portions 38 b and 48 b maybe larger, and the first portions 38 a and 48 a and the second portions38 b and 48 b may be connected to each other, respectively, at a longerdimension. Then, each width of the second portions 38 b and 48 b maycontinuously or stepwise narrow with approach toward bottom (see FIG.6A).

Further, the second portions 38 b and 48 b were provided along the wideside surface of the battery case 10. However, the second portions 38 band 48 b may be provided along the narrow side surface of the batterycase 10. In this case, the second portions 38 b and 48 b may be furtherbent, thereby to be bonded to the collector regions 32 c and 42 c of theelectrode body 20, respectively. For example, for the second portions 38b and 48 b, as shown in FIG. 6C, at least the lower portions thereof tobe bonded to the collector regions 32 c and 42 c of the electrode body20 each may be bifurcated by a slit. When each lower end of the secondportions 38 b and 48 b is bifurcated, the collector part of the woundtype electrode body 20 can be divided into two parts with reference tothe winding axis WL, and bound, respectively. These can be connected torespective bifurcated portions of the second portion 38 b in a dividedmanner, respectively. With such a configuration, in bonding between thewound type electrode body 20 and the collector members 38 and 48, thedeformation amount and the load applied to the collector regions 32 cand 42 c can be reduced. Further, this is also preferable in that theimpregnation of the electrolyte into the wound type electrode body 20can be promoted. Incidentally, in this case, the ribs 38 c and 48 c maybe desirably provided one each above respective centers in respectivewidth directions of respective bifurcated portions of the secondportions 38 b and 48 b (the width direction of the narrow side surface,the thickness direction of the battery case). Provision of respectiveones of the ribs 38 c and 48 c at respective second portions 38 b and 48b is also preferable in terms of enhancing the strengths of the secondportions 38 b and 48 b.

In the embodiment, the electrode body was a wound type electrode body.However, the electrode body may be a sheet type electrode body. When theelectrode body is a sheet type electrode body, as shown in FIG. 6B, thesecond portions 38 b and 48 b of the collector members 38 and 48 areeach not required to have the curved part 38S. Also in that case, thedimensions of the ribs 38 c and 48 c preferably fall within theforegoing range.

In the embodiment, for the collector members 38 and 48, the secondportions 38 b and 48 b were set so as to extend downwardly along thewide side surface. However, the aspect of attaching the collectormembers 38 and 48 to the battery case 10 is not limited to this. Forexample, the second portions 38 b and 48 b of the collector members 38and 48 may be set so as to downwardly extend along the narrow sidesurface. In this case, as shown in FIG. 6C, the second portions 38 b and48 b may be bonded at their respective two parts to the collectorregions 32 c and 42 c of the electrode body, respectively. For example,as seen from the narrow side surface side, the second portions 38 b and48 b are each bifurcated into two parts extending downwardly, and thewound type electrode body 20 is divided into two parts on the 3 o'clockside and the 9 o'clock side along the winding axis WL. Then, respectiveones of the bifurcated parts of the second portions 38 b and 48 b may bebonded to the electrode body 20 on the 3 o'clock side, and respectiveothers of the bifurcated parts may be bonded to the electrode body 20 onthe 9 o'clock side. At this step, the ribs 38 c and 48 c may beprovided, one for each of respective bifurcated parts of the secondportions 38 b and 48 b. Further, the bifurcated parts of the secondportions 38 b and 48 b may be respectively twisted so as to be inparallel with the collector regions 32 c and 42 c, and to be bonded tothe collector regions 32 c and 42 c, respectively.

Up to this point, the present invention was described in details.However, these are merely illustrative, and do not limit the appendedclaims. The technology described in the appended claims include variousmodifications and changes of the foregoing specific examples.

What is claimed is:
 1. A secondary battery, comprising: a battery case;an electrode body in which a positive electrode, a negative electrode,and a separator are stacked, with the positive electrode and thenegative electrode being insulated from each other by the separator; anda collector member connected to the battery case and the electrode body,wherein the positive electrode includes a positive electrode collectorincluding an active material layer forming region, an insulation layerforming region adjacent to the active material layer forming region, anda collector region adjacent to the insulation layer forming region, apositive electrode active material layer including a positive electrodeactive material provided on a surface of the active material layerforming region, and an insulation layer provided on a surface of theinsulation layer forming region, the collector member includes a firstportion, and a second portion continuous to the first portion and bentrelative to the first portion, the first portion is fixed to the batterycase, the second portion is connected, at an end thereof on an oppositeside to the bent portion, to the collector region, the collector memberfurther including a rib integrally formed, at the bent part, with thefirst portion and the second portion; and wherein the rib has a lengththat is shorter than a space between a top of the electrode body and thefirst portion of the collector member, and a width that is half or lessthan a thickness of the electrode body.
 2. The secondary batteryaccording to claim 1, wherein the rib is connected, among surfaces ofthe first portion and the second portion, to a surface on an oppositeside to the electrode body.
 3. The secondary battery according to claim1, wherein the collector member includes the first portion, the secondportion, and the rib, which are continuously and integrally formed, andis at least one of a bent product and a pressed product of asheet-shaped metal.
 4. The secondary battery according to claim 1,wherein the battery case is a square battery case including a case mainbody having an opening, and a lid member for covering the opening, thefirst portion is connected to an inner surface of the lid member, thesecond portion is bent along any one surface of the case main bodysurrounding the opening, and a length (L_(C)) of the collector memberfrom the first portion to an extreme end of the end of the collectormember and a length (L_(R)) of a dimension of the rib in a directionalong the length (L_(C)) satisfy following relationship:L_(R)≥0.1×L_(C).
 5. The secondary battery according to claim 1, whereinthe battery case is a square battery case including a case main bodyhaving an opening, and a lid member for covering the opening, the firstportion is connected to an inner surface of the lid member, the secondportion is bent along any one surface of the case main body surroundingthe opening, a thickness (T_(C)) of a dimension of the collector memberin a direction orthogonal to the one surface of the second portion and athickness (T_(R)) of a dimension in a direction in parallel with the onesurface of the rib satisfy following relationship: T_(R)≥0.4×1/T_(C). 6.The secondary battery according to claim 1, wherein the battery case isa square battery case including a case main body having an opening, anda lid member for covering the opening, the first portion is connected toan inner surface of the lid member, the second portion is bent along anyone surface of the case main body surrounding the opening, a thickness(T_(C)) of a dimension in a direction orthogonal to the one surface ofthe second portion and a width (W_(R)) of a dimension of the collectormember in a direction along the thickness (T_(C)) of the rib satisfyfollowing relationship: W_(R)≥0.25×1/T_(C).
 7. The secondary batteryaccording to claim 1, wherein the electrode body is a wound typeelectrode body in which the positive electrode, the negative electrode,and the separator which are lengthy are stacked and wound.
 8. Thesecondary batter according to claim 1, wherein the rib has a length thatis shorter than a space between top of the electrode body and the firstportion of the collector member.